Types of ambiguity I. Lexical ambiguity "I saw a bat." bat = flying mammal / wooden club? saw = past tense of "see" / present tense of "saw" (to cut with a saw.) II. Syntactic ambiguity. III. Semantic ambiguity. Even after the syntax and the meanings of the individual words have been resolved, there are two ways of reading the sentence. The handout "Guide to Expressing Facts in a First-Order Language" has a lot of examples of ambiguity in quantifier scope and logical structure. E.g. in "Lucy owns a parrot that is larger than a cat", "a parrot" is extenstensionally quantified, "a cat" is either universally quantified or means "typical cats." "The dog is chasing the cat." vs. "The dog has been domesticated for 10,000 years." In the first sentence, "The dog" means to a particular dog; in the second, it means the species "dog". "John and Mary are married." (To each other? or separately?) Compare "John and Mary got engaged last month. Now, John and Mary are married." vs. "Which of the men at this party are single? John and Jim are married; the rest are all available." "John kissed his wife, and so did Sam". (Sam kissed John's wife or his own?) IV. Anaphoric ambiguity. A phrase or word refers to something previously mentioned, but there is more than one possibility. "Margaret invited Susan for a visit, and she gave her a good lunch." (she = Margaret; her = Susan) "Margaret invited Susan for a visit, but she told her she had to go to work" (she = Susan; her = Margaret.) "On the train to Boston, George chatted with another passenger. The man turned out to be a professional hockey player." (The man = another passenger). "Bill told Amy that he had decided to spend a year in Italy to study art." "That would be his life's work." (That = art) "After he had done that, he would come back and marry her." (That = spending a year in Italy) "That was the upshot of his thinking the previous night" (That = deciding) "That started a four-hour fight." (That = telling Amy) In many cases, there is no explicit antecedent. "I went to the hospital, and they told me to go home and rest." (They = the hospital staff.) V. Non-literal speech. "The White House announced today that ..." ("White House" = Clinton's staff) (Mentonymy) "The price of tomatoes in Des Moines has gone through the roof" (= increased greatly) Metaphor. VI. Ambiguity in textual connections "John slumped down in his chair with a beer, in front of the evening news. He was tired." (i.e. when he slumped) "John worked for fourteen hours on the Foster project, and then was stuck in a traffic jam coming home. He was tired." (i.e. after working and being stuck). VII. Ambiguity of user intent "Do you know what time it is?" (= "Please tell me what time it is" or sometimes "You are very late.") Indirect speech act. ******************************************************************** A perfectly typical, not contrivedly literary, actual example, from "Nice disguise: Alito's frightening geniality" by Andrew M. Siegel (The New Republic 11/14/05). If you are a fan of the justices who fought throughout the Rehnquist years to pull the Supreme Court to the right, Alito is a home run --- a strong and consistent conservative with the skill to craft opinions that make radical results appear inevitable and the ability to build trusting professional relationships across ideological lines. Metaphors: "fought", "pull to the right", "home run", "craft", "build", "across ... lines". (Probably "home run" was the only conscious use of a metaphor.) Lexical ambiguities: "fan", "strong", "consistent", arguably "conservative", "opinions", "results", "inevitable", "professional". (The line between metaphor and lexical ambiguity is very unclear.) Syntactic ambiguities: Does "who fought ..." attach to "fan" or "justices"? Does "to the right" attach to "Court", "pull", "years", "fought", "justices" or "fan"? Is "and the ability" conjoined to "opinions" or "the skill" or "conservative"? Does "across ideological lines" attach to "relationships" or "build"? (The last is an example of the phenomenon, not at all rare, of an ambiguity that makes no actual difference; the meaning of either reading is the same.) Anaphoric ambiguity: Who are the implicit subject and object of "trusting"? Semantic ambiguity: "the skill ... the ability": Do these denote unique ontological entities? If not, what do they denote? The hardest part is to find the logical structure, which is, I would argue, "Since Alito is a strong and consistent conservative ... therefore if you are a fan ... then your opinion should be that Alito is a home run." Notice that "your opinion should be" is omitted in the sentence; the linguistic practice of deleting elements and leaving them implicit is known as ellipsis. Notice also that though syntactically "home run" and "strong and consistent conservative" are in apposition, logically they are entirely separate. The author is presenting it as fact that Alito is a strong and consistent conservative with the skill etc. but that Alito is a "home run" is not a fact, it is the presumed opinion of the hypothetical "you". Techniques of ambiguity resolution. I. Syntactic constraints. II. Frequency. (Particularly for lexical ambiguity.) Prefer the most common meaning of a word. "I saw the table." "saw" = past tense of see is much more common than "saw" = present tense "cut with a saw." III. Frequency in context. In context = dinner, "pitcher" means "container of liquid" In context = baseball, "pitcher" means "thrower of ball." IV. Spreading activation. Concepts and words are nodes connected in memory. When a word is mentioned the connected conceptual nodes are activated. A highly activated node is chosen for focus. E.g. "The pitcher picked up the bat" "The eagle saw the bat." Nodes: (liquid container) -- "pitcher" -- (ball-thrower) --- (baseball) | (flying mammal) --- "bat" --- (wooden club) ---------------| | (animal kingdom) --- (noble bird) --- "eagle" With the first sentence the baseball node gets lit up by both "pitcher" and "bat", causing the interpretations of ball-thrower and wooden club to be preferred. With the second sentence the animal kingdom node gets lit up by both bat and eagle. V. Selectional restrictions. (= semantic constraints) Concept A can only combine with concept B in mode Z if A or B have specified features. E.g. "The bat ate its dinner." The subject of "ate" is generally animate. Therefore "bat" means "flying mammal" not "wooden club." "The sick bat lay on the ground." The adjective "sick" generally modifies animate objects. Hence "bat" = flying mammal. "The broken bat lay on the ground." The adjective "broken" generally modifies inanimate objects. Hence "bat" is a wooden club. "The clock is fast." vs "The horse is fast." vs. "The clothes are fast." vs. "The slopes are fast." vs. "The knot is fast." "fast" meaning "showing a time later than correct." applies only to a time-piece. "fast" meaning "speedy" applies only to a mobile object. "fast" meaning "trendy" applies only to an object of conspicuous display.. "fast" meaning "inducing speedy movement" applies only to a context of movement. "fast" meaning "secure" applies only to a fastening. "The horse ran up the hill. It was very steep." vs. "It soon got tired." "Steep" applies to surfaces, hence "it" = hill. "Tired" applies to animate objects; hence "it" = horse. "I went to the hospital on 13th street" vs. "on Wednesday" "on